Compression test

[Joker2]

Can anyone tell me the proper way to do a compression check on a 1995 150 HP Ocean Pro ? Thanks

[tsubaki]

Can't say it's correct but I usually remove all the plugs, hold the throttle butterflies wide open and pump each cylinder till the gauge levels out.
This is done using a remote start switch (jumping the solenoid) with the key off.
Hoping for no more than 10% difference between the cylinders.
Never been able to determine what the "correct compression" for each engine was. With the 150's, I expect 90psi and above is pretty good on the crossflows, I would think the loopers would be higher.

[Joker2]

Sounds good, butterflys open is the same as manually holding the throttle full open at the engine corrrect? Jumping the selenoid is the same as cranking the engine with the safety lanyard (kill switch ) disconnected right? Just curious because other things i have heard say that but I trust you guys on this site.

[tsubaki]

I didn't think about the kill switch doing the same thing but yes.
The wide open throttle lets all available air into the cylinders.
Some people will say do it after warmed up or with oil to improve the accuracy or cold is the best test.
It's gonna depend on a lot of factors. For me, if it don't perform a good test cold, the engine's questionable period.

[Joker2]

another question! is the seafoam engine treatment I have heard about on this site the same as the Evinrude engine tune ?

[Destroyer]

Originally Posted by Joker2

another question! is the seafoam engine treatment I have heard about on this site the same as the Evinrude engine tune ?

Seafoam is an aftermarket product that keeps your carbs and injectors clean of residue, shelac, etc. It's got a good, well deserved, reputation within the boating and automotive industry. Simply put, it does what it's advertised to do. While I've never used it, I'm sure that the Evinrude Engine Tune does everything that it's advertised to do also.